Packaging Machine For Vacuum Skin Packaging

ABSTRACT

A vacuum-skin packaging machine for sealing film onto a tray containing a product includes a vacuum system. The vacuum system includes a vacuum pump, piping, and valves. The machine includes a top structure and a bottom structure defining a vacuum chamber in communication with the vacuum pump via the piping. An actuating mechanism transitions the top structure and the bottom structure between an opened state where they are separated and a closed state where they are sealed. A platen-movement mechanism moves a platen to the chamber while the top and bottom structures are in the opened state. The platen holds the trays. A heating plate heats the film while the top and bottom structures are in the closed position. The heated film is forced against the trays in response to a valve venting a region of the vacuum chamber adjacent to the heated film.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. Provisional Patent Application No. 62/008,863 titled “Packaging Machine For Vacuum Skin Packaging,” filed Jun. 6, 2014, which is incorporated herein by reference in its respective entirety.

COPYRIGHT

A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.

FIELD OF THE INVENTION

The present invention relates generally to a packaging apparatus and methods and, more particularly, to a packaging machine for use in a vacuum-skin packaging process.

BACKGROUND OF THE INVENTION

One common packaging format for fresh meat that is cut at a retail store is PVC-wrapped foam tray. The clear PVC film is very permeable to oxygen and allows the meat to maintain the preferred red color for 3-5 days. After packaging, the color deteriorates until it becomes unsalable.

Today, most fresh meat is cut and packaged at a centrally located factory in a different type of packaging format that protects the color for a longer time because more than 5 days are required to properly distribute the product. Further, most retailers want a color life for the meat that extends for more than a week after they receive it in order to reduce discounts and losses. This form of packaging is termed “case ready.” As the name implies, the case-ready packaging format involves fabricating and packaging the finished retail cut so as to make it ready for the display case, even to the point of pricing and/or labeling with UPC codes to make inventory control easy for the retailer to which it will be shipped.

Because fresh meat typically deteriorates quickly after cutting and exposing the meat surface to atmospheric oxygen, case-ready packaging formats have been designed to delay this deterioration. The case-ready package is called upon to extend the consumer preferred color for more than 14 days, which is typically enough time to distribute the product and display for retail sale. Most of these case-ready packaging formats use machines that eliminate oxygen in order to protect color and delay bacterial spoilage.

A common approach to eliminate oxygen is to modify the atmosphere surrounding the meat within the package. The typical modified atmosphere package (MAP) is formed on equipment using pre-formed trays and rollstock film for lidding. The gas inside the package is modified with nitrogen, carbon monoxide, carbon dioxide and/or oxygen at controlled levels found to be effective at extending shelf life of the specific food article being packaged. The equipment function involves indexing filled preformed trays into a vacuum chamber where the atmosphere is sucked out of the chamber. The rollstock film is indexed into the chamber at the same time and heated during evacuation. The modified gas of choice is vented into the chamber before a seal plate compresses the film onto the preformed tray flange to hermetically seal it to the tray, thereby creating the package that is then trimmed apart from adjacent packages using a cutting system. The film stays with the trays as they are cut and then rolled onto a take-up roller to remove scrap generated by the cutting action. As such, a “MAP” packaging format involves a gas that is actively flushed into the headspace of a hermetically sealed package.

Another common case-ready packaging format employs a master package comprised of flexible film. The master package is flushed with an oxygen-free atmosphere that contains carbon monoxide. Several PVC wrapped trays with meat are contained within the master package. Since the PVC film is gas permeable, the carbon monoxide gas causes the meat to bloom to the consumer preferred red color. Usually, six to eight trays are packed into a preformed bag or pouch at the regional facility where snorkel equipment is used to modify the atmosphere and hermetically seal the bag or pouch. Shelf life can be extended to upwards of 30 days. However, the color of the meat becomes unacceptable in only 3-5 days after removal from its master package.

Another approach is vacuum packaging with flexible films on horizontal form fill seal machines (HFFS machines). They employ two rolls of flexible film. One is referred to as the top or non-forming film and the other as the bottom or forming film. The bottom film is generally formed into a size and shape that accepts the meat article to be packaged. The formed film pocket is covered with the top film as it indexes into an evacuation chamber. The machine evacuates air from inside the package and then hermetically seals the top non-forming film to the bottom forming film to create the package. Upon venting, the packaging material collapses around the product. The absence of oxygen slows down the oxidation that causes rancidity. The product's quality and freshness does not degrade during frozen storage. Products in a vacuum package can be stored in the freezer for greater than six months.

A vacuum skin package (VSP) is a type of vacuum packaging where the top film is heated and formed around the article to be packaged. In a VSP machine, one object is to form the film uniformly to the shape of the food article and seal it to the tray. The end result is a film that conforms to the product without wrinkles or weak spots and a film to tray seal that is continuous up to the edge of the product. The tray acts as a bottom support member for the product. As such, a VSP packaging format uses a flexible film that is heated and formed over the top of a package in a manner that conforms to the shape of the product. It thereby forms an invisible skin to enhance product appearance. The present invention is directed to improvements to a vacuum-skin packaging machine.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, a method for providing a vacuum-skin packaging (VSP) for products on trays uses a vacuum chamber defined by a top structure and a bottom structure. The method includes (i) while the bottom structure is retracted away from the top structure, automatically moving a platen along a path that extends into the vacuum chamber, the platen containing one or more of the trays; (ii) positioning a film over the platen; (iii) after the platen is positioned within the vacuum chamber, moving the bottom structure upwardly against the top structure so as to form a seal between the top structure and the bottom structure; (iv) creating a vacuum within the vacuum chamber, the film dividing the vacuum chamber into an upper volume and a lower volume; (v) heating the film; (vi) venting the upper volume above the platen to force the heated film onto the platen and the one or more tray; (vii) retracting the bottom structure from the top structure of the vacuum chamber; and (viii) automatically moving platen along the path out of the vacuum chamber.

According to another aspect of the invention, a vacuum-skin packaging machine for sealing film onto a tray containing a product includes a vacuum system. The vacuum system includes a vacuum pump, piping, and valves. The machine further includes a top structure and a bottom structure defining a vacuum chamber. The chamber is in communication with the vacuum pump via the piping. An actuating mechanism transitions the top structure and the bottom structure between (i) an opened state whereby the top structure and the bottom structure are separated and (ii) a closed state whereby the top structure and the bottom structure are sealed together. A first platen-movement mechanism moves a platen from an in-feed position into the chamber while the top structure and bottom structure are in the opened state. The platen holds the trays. A heating plate heats the film while the top structure and bottom structure are in the closed position. The heated film is forced against the platen and the trays in response to one or more of the valves venting a region of the vacuum chamber adjacent to the heated film.

In yet another aspect of the invention, a vacuum-skin packaging machine for sealing film onto a tray containing a product comprises a vacuum system. The vacuum system includes a vacuum pump, piping, and valves. The machine includes a top structure and a bottom structure defining a vacuum chamber. The top structure and the bottom structure is transitionable between (i) an opened state whereby the top structure and the bottom structure are separated and (ii) a closed state whereby the top structure and the bottom structure are sealed together to create the vacuum chamber. A moveable platen is located within the vacuum chamber. The movable platen holds the tray. A stationary heated plate is located within the top structure. The stationary heating plate heats the film while the top structure and bottom structure are in the closed state. The heated film is forced against the platen and the tray in response to one or more of the valves venting a region of the vacuum chamber adjacent to the heated film.

In yet another aspect of the invention, a packaging machine for vacuum sealing a film onto a tray containing a product comprises a housing and a vacuum system located within the housing. The vacuum system includes a vacuum pump, piping, and valves. The machine includes a top structure and a bottom structure defining a chamber. The top structure and the bottom structure is transitionable between (i) an opened state whereby the top structure and the bottom structure are separated and platens can enter and exit the chamber and (ii) a closed state whereby the top structure and the bottom structure are sealed together to create a vacuum chamber. The machine includes a continuous platen-movement path on which the platens move from a loading station where trays are loaded on the platens, into the vacuum chamber where the film is sealed against the trays, to a removal station where the filmed trays are removed from the platens, and back to the loading station.

In a further aspect, the invention is a method of vacuum-skim packaging that includes automatically moving a plurality of platens along a continuous path from a loading station where the trays are loaded on the platens, to the vacuum chamber where the film is sealed against the trays, to a removal station where the filmed trays are removed from the platens, and back to the loading station. Each of the platens contains one or more of the trays. Each of the platens receives a heated film while in the vacuum chamber.

In a further aspect, the present invention is a platen for receiving trays with product. The platen comprises a main body and a plurality of polymeric inserts. The main body includes a plurality of tray-receiving regions and a plurality of grooves that are located around the plurality of tray-receiving regions. The plurality of polymeric inserts is located within the plurality of grooves. The plurality of polymeric inserts is positioned to contact a film that is placed over the product and the tray. The plurality of polymeric inserts engage cutting mechanisms that cut the film around the trays. Preferably, the platens are a metal, such as aluminum, and the polymeric inserts are nylon.

Additional aspects of the invention will be apparent to those of ordinary skill in the art in view of the detailed description of various embodiments, which is made with reference to the drawings, a brief description of which is provided below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a free-standing VSP machine according to a first embodiment of the present invention.

FIG. 2 is a plan view of one type of platen holding four trays that can be used in the VSP machine of FIG. 1.

FIG. 3 is a side cross-sectional of the VSP machine of FIG. 1.

FIG. 4 is a perspective cross-sectional of the VSP machine of FIG. 1.

FIG. 5 is a perspective view of the free-standing VSP machine of FIG. 1 with a loaded platen being fed into the vacuum chamber.

FIG. 6 is a perspective view of the free-standing VSP machine of FIG. 1 with the loaded platen located within vacuum chamber.

FIG. 7 is a perspective view of the free-standing VSP machine of FIG. 1 with the vacuum chamber being closed around the loaded platen.

FIG. 8 is a perspective view of the free-standing VSP machine of FIG. 1 with the vacuum chamber being closed around the loaded platen, and a second loaded platen ready for entry into the vacuum chamber.

FIG. 9 is a perspective view of the free-standing VSP machine of FIG. 1 with the vacuum chamber opened around the loaded platen in which the four trays have received film over their upper surfaces for packaging, and the second loaded platen is ready for entry into the vacuum chamber.

FIG. 10 is a perspective view of the free-standing VSP machine of FIG. 1 with the second loaded platen being transferred into the vacuum chamber, and the first loaded platen is exiting the vacuum chamber.

FIG. 11 is a perspective view of the free-standing VSP machine of FIG. 1 with the vacuum chamber enclosing the second loaded platen, and the four trays within the first loaded platen having the excess film cut prior to removal of the four trays from the platen.

FIG. 12 is a perspective view of a free-standing VSP machine according to a second embodiment of the present invention in which the platens move in a continuous cyclical path after being loaded with trays in a loading region.

FIG. 13 is a perspective view of the free-standing VSP machine of FIG. 12 in which a first loaded platen is being moved towards an entry position for the vacuum chamber along the continuous cyclical path.

FIG. 14 is a cross-sectional perspective view of the free-standing VSP machine of FIG. 12 in which a loaded platen has been moved into the vacuum chamber and an additional loaded platen is located at the entry position for the vacuum chamber.

FIG. 15 is a cross-sectional perspective view of the free-standing VSP machine of FIG. 12 in which a loaded platen is removed from the vacuum chamber at the same time that the other loaded platen is moved into the vacuum chamber.

FIG. 16 is a cross-sectional perspective view of the free-standing VSP machine of FIG. 12 in which the vacuum chamber is closed around a loaded platen, while another loaded platen is located at an exit position for the vacuum chamber along the continuous cyclical path.

FIG. 17 is a cross-sectional perspective view of the free-standing VSP machine of FIG. 12 in which a loaded platen is moved through an automatic film-cutting region along the continuous cyclical path.

FIG. 18 is a cross-sectional perspective view of the free-standing VSP machine of FIG. 12 in which a loaded platen is moved from a film-cutting region to the tray-removal region along the continuous cyclical path.

FIG. 19 is a cross-sectional perspective view of the free-standing VSP machine of FIG. 12 where the trays are being removed from one platen, a previously unloaded platen is in a position to be transferred towards the loading position, and another loaded platen remains within the vacuum chamber along the continuous cyclical path.

FIG. 20A illustrates a platen having cutting-element receiving grooves and inserts within those grooves.

FIG. 20B illustrates a cross section of the platen taken along line 20B-20B in FIG. 20A.

FIG. 20C illustrates a cross section of the platen taken along line 20C-20C in FIG. 20A.

While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated. For purposes of the present detailed description, the singular includes the plural and vice versa (unless specifically disclaimed); the words “and” and “or” shall be both conjunctive and disjunctive; the word “all” means “any and all”; the word “any” means “any and all”; and the word “including” means “including without limitation.”

FIG. 1 illustrates a VSP machine 10 that includes a housing 12 in which a vacuum chamber resides. The VSP machine 10 sequentially receives independent platens 14, each of which includes one or more trays 16 that have a product positioned thereon. The VSP machine 10 seals a film, which is advanced from a film roll 20, over the top of the product on the trays 16 riding on the platen 14, as will be described in more detail below.

FIG. 2 illustrates one type of platen 14 that may be used within the VSP machine 10. As shown, the platen 14 includes four trays 16 having a piece of meat 18 positioned on the upper surface of the tray 16. The platen 14 includes interior structures that are adapted to receive the four trays 16. While the platen 14 may be designed with different interior structures and dimensions to receive different shapes and sizes of trays 16, the external dimensions of each of the types of the platens 14 should be constant in order to fit within the VSP machine 10. Accordingly, the same VSP machine 10 can be used to provide vacuum skin-packed trays of various styles and shapes by changing the type of platen.

As show in FIGS. 3 and 4, the platens 14 are transferred along a path within the machine 10 having three primary positions. The platen 14 a is at an entry position and lacks a film (i.e., it is a non-filmed platen 14 a). The platen 14 b is in the packaging position within the region of the vacuum chamber 30 where it will receive film. And, the platen 14 c is located at the exit position and has received the film (i.e., it is a filmed platen 14 c).

FIGS. 3 and 4 also illustrate the various components within the housing 12 of the VSP machine 10. The vacuum chamber 30 is defined by a bottom structure 32 and a top structure 34. The bottom structure 32 is movable relative to the top structure 34, thereby permitting entry of each of the platens 14 into the vacuum chamber 30. After a platen 14 has entered the chamber 30, the bottom structure 32 moves towards and is sealed against the top structure 34 of the vacuum chamber 30. Within the vacuum chamber 30, a stationary platform 36 supports the platen 14 and is held in place via a pair of elongated support members 37. A heating plate 38 (preferably perforated and stationary) is also located within the chamber 30 adjacent to the top structure 34. The heating plate 38 heats the film from the web 20 after the vacuum chamber 30 has been evacuated so as to put the film in a state that allows it to be easily attached to each of the trays 16 on the platen 14.

One or more evacuation pumps 40 may be used to pull the vacuum within the vacuum chamber 30. Because the film located above the platen 14 divides the vacuum chamber 30 into a lower volume and upper volume, lower piping 42 is connected to the evacuation pump 40 to remove the air from the lower volume located below the film (i.e. the region surrounding the platen 14 which holds the trays 16 and the product 18). The lower piping 42 includes internal air conduits within the pair of elongated support members 37 that support the stationary platform 36. The elongated support members 37 and/or the stationary platform have openings to permit the evacuation and the venting of the lower volume below the film. And, upper piping 44 (only a portion of which is shown) is connected to the evacuation pump 40 to remove air from the upper volume located above the film. Because the upper volume is smaller, obtaining a vacuum is easier in the upper volume than the lower volume. Valves are positioned within the lower piping 42 and upper piping 44 to initiate the evacuation, and to release the evacuation.

The film from the web 20 is advanced over one or more rollers 50 before entering the region of the vacuum chamber 30 when the bottom structure 32 is in its retracted position away from the top structure 34. A film-advancing mechanism 52, which may include one or more pneumatically activated pistons, grabs the film in a region adjacent to the roller 50 and pulls it across the vacuum chamber 30. A cutting mechanism 54, which includes one or more knives, cuts the film in the region adjacent to the roller 50, which is outside the vacuum chamber 30, such that the platen 14 and the trays 16 can be removed from the opposing side of the VSP machine 10 once the packaging process has been complete. The cutting mechanism 54 preferably cuts the film when the bottom structure 32 and the top structure 34 are engaging each other to form the enclosed vacuum chamber. The cutting mechanism 54 can also be pneumatically activated.

Various devices can be used to move the bottom structure 32 of the vacuum chamber 30. In one preferred embodiment, a pneumatically actuated piston 60 forces the bottom structure 32 upwardly against the top structure 34. And, after the packaging process within the vacuum chamber 30 has been completed, the piston 60 permits the bottom structure 32 to be retracted from the top structure 34. The bottom structure 32 of the vacuum chamber 30 includes two openings with sealing structures (such as O-rings) that engage the pair of elongated support members 37 when the bottom structure is moving between the opened state and the closed state.

To remove the filmed platen 14 c from the machine 10, a power driven roller 62 grabs the underside of the platen 14 and advances it away from the machine 10. The film, which has been sealed to each of the four trays 16 may be cut automatically, or manually, on the platen 14. The platen 14 may be designed with grooves to receive the cutting edges of the tools used to separate the sealed film into four distinct pieces that cover the four trays 14, respectively. Excess film is then removed and discarded.

As will be discussed below with respect to FIGS. 5-10, the VSP machine 10 includes actuated slide elements 70 that force each of the platens 14 into the machine 10. As one platen 14 enters the machine 10 through the movement of the slide element 70, the entering platen 14 a forces the platen 14 b position within the vacuum chamber 30 to move outwardly towards the power-driven roller 62. Accordingly, each of the platens 14 exits the machine 10 through a combination of the force exerted on it from the subsequent platen that is entering the vacuum chamber 30 and the force of the power-driven roller 62.

In summary, the present invention involves the platen 14 that is tooled to receive at least one, and preferably several (such as four or more) preformed trays 16 having a unique shape. The platen 14 is used to transport the trays 16 containing products (e.g., freshly cut meat) into and out of the vacuum chamber 30. One platen 14 can hold several trays as it is indexed onto the stationary platform 36 within the vacuum chamber 30. The bottom structure 32 of the evacuation box moves upward to surround the platen 14 and, in combination with top structure 34, forms the vacuum chamber 30 that encloses the platen 14.

To seal the film to the trays 16, after chamber 30 is evacuated, it is vented first from the upper volume within the top structure 34 adjacent to the heating plate 38 that is used to heat a film located over the trays 14 within the vacuum chamber 30. The venting of the upper volume of the chamber 30 collapses the heated film onto the platen 14 with the trays 16 holding the product 18. The venting of the lower volume below the film within the bottom structure 32 then occurs, and the film web is cut by the cutting mechanism 54 so that when the bottom structure 32 of the vacuum chamber 20 retracts to open the chamber 30, the film stays with the tray-holding platen 14 at a level several inches below the film's original in-feed position. The now-filmed platen 14 is removed from the chamber 30 and transferred to another station for film cutting, before removing the trays 16 from the platen 14. Multiple platens 14 may be used to facilitate the machine functions that are required to create a vacuum skin package and increase production capacity.

FIGS. 5-11 illustrate a cycle by which a non-filmed platen 14 a is initially placed on an in-feed table 72, moves through the vacuum chamber 30 where it receives film, and exits the vacuum chamber as a filmed platen 14 c. In FIG. 5, the non-filmed platen 14 a is positioned on an in-feed table 72 where it will be moved by a slide element 70 into the vacuum chamber 30. The slide element 70 is releasably locked onto the platen 14 a, usually by a spring-loaded mechanism. The slide element 70 is controllably movable, usually under the power of a pneumatic piston, and advances the platen 14 a underneath the top structure 34 of the vacuum chamber 30. FIG. 6 illustrates the platen 14 a at a location directly under the top structure 34 of the vacuum chamber 30 and the platen 14 a is supported on stationary platform 36. At this point, the film from the roll 20 has been advanced by the film-advancing mechanism 52 and is located directly above the platen 14 a within the chamber 30.

In FIG. 7, the piston 60 has been actuated to cause the lower structure 32 of the vacuum chamber 30 to move upwardly and be positioned against the top structure 34 of the vacuum chamber 30. Once the lower structure 32 has been sealed against the top structure 34, the vacuum pump 40 can begin drawing the air out of the vacuum chamber 30. FIG. 7 also shows the slide element 70 extending along the in-feed table 72 in its original position such that it now awaits another non-filmed tray 14 a that requires film. Accordingly, once the slide element 70 is in its original position, and the operator of the machine 10 can place an additional non-filmed tray 14 a on the in-feed table 72 such that it is engaged within the slide element 70.

In FIG. 9, the process of placing the film on the platen 14 within the chamber 30 is complete such that it is now a filmed platen 14 c. The film has been sealed against each of the four trays 16 located within the filmed platen 14 c. The piston 60 has caused the lower structure 32 of the vacuum chamber 30 to be retracted. In FIG. 10, the slide element 70 advances the next non-filmed platen 14 a into the vacuum chamber 30, thereby causing the filmed platen 14 c to be pushed out of the vacuum chamber 30. FIG. 11 illustrates the completion of the cycle in that the second non-filmed platen 14 a is now located within the chamber 30 as the piston 60 has caused the lower structure 32 to be moved upwardly against the top structure 34. The filmed platen 14 c has been driven by the power-driven roller 62 further outwardly, such that it is advanced to the station where the film on the filmed platen 14 c can be cut (manually or automatically). Each tray 16 has its own individual film located over the product 18 held on the upper surface of the tray 16.

In summary, the machine 10 provides for a manufacturing method of a vacuum skin package where the skin packaging film is heated and formed over the product 18 as it sits on a flat preformed tray 16. The platen 14, which is tooled to the shape of the preformed tray 16, is used to transport the tray 16 into and out of the vacuum chamber 30. After loading a platen 14 containing the trays 16 onto the in-feed table 70. The pneumatic slide element 72 (or a piston) pulls the platen 14 onto the stationary platform 36. At the same time, a pneumatic slide or piston of the film-advancement mechanism 52 pulls the film into the chamber 30 just below the heating plate 38, which is housed within the top structure 34 of the evacuation chamber 30. After the film and platen 14 are in place, the bottom structure 32 of the evacuation chamber 30 is pushed upward to surround the platen 14 and the evacuation chamber 30 is closed. The chamber 30 is evacuated with a vacuum pump 40 by opening bottom and top evacuation valves within the lower piping 42 and the upper piping 44. The upper volume (within the top structure 34) of the evacuation chamber 30 above the film is more rapidly evacuated due to its smaller volume and the film sucks tightly to the perforated heating plate 38. After chamber evacuation and film heating, the upper volume (within the top structure 34) of the chamber 30 above the film is vented prior to venting the lower volume below the film. The venting forces the heated film onto the trays 16 being held by the platen 14. The film web is cut with a piston-powered knife 54 so that when the bottom portion 32 retracts to open the chamber 30, the film stays with the tray-holding platen 14 several inches below the in-feed film web line. The filmed platen 14 c is removed from the chamber when the pneumatic slide element 72 piston pulls another non-filmed platen 14 a onto the stationary platform 36. The non-filmed platen 14 a entering the chamber 30 pushes the filmed platen 14 c onto a power-driven roller 62. The filmed platen 14 c is then free to be fed into another separate machine for film cutting before removing the trays 16 from the platen 14. By use of multiple platens 14, increased production capacity can be achieved.

FIGS. 12-19 illustrate a second embodiment of a VSP machine 110, which has vacuum and film-placement operations that are functionally the same as the machine 10 in FIGS. 1-11. However, unlike the machine 10 of FIGS. 1-11, the machine 110 of FIGS. 12-19 permits the platens 114 to move along a continuous cyclical path, such that an end point along the path is located at a position where platens 114 can be again loaded with trays and product. The reference numerals in the machine 110 of FIGS. 12-19 have been replaced by 100-series reference numerals to identify structures similar to those in the machine 10 of FIGS. 1-11.

In FIG. 12, the machine 110 has a housing 112 that contains a film roll 120, which has film that will advance between a bottom structure 132 and a top structure 134 of a vacuum chamber 130. A plurality of platens 114 contains a plurality of trays 116 with a plurality of product 118 thereon. The plurality of platens 114 cyclically move along a continuous path. Specifically, a first platen 114 a is located at a loading station where the trays 116 and the product 118 are placed on the first platen 114 a. At that time, there is a second previously loaded platen 114 b (not shown in FIG. 12) that is located within the vacuum chamber 130 between the bottom structure 132 and the top structure 134. The second platen 114 b is in the process of receiving a heated film over its trays 116 and product 118, through the same process described above with respect to FIGS. 1-11. Meanwhile, a third platen 114 c has completed the cycle and is at an end point along the path, where it is awaiting to receive trays 116 and product at the loading station after the first platen 114 a has vacated that station.

To move the platens 114, a pair of transfer elements 180 moves the platens 114 along at least a portion of the path. In one preferred embodiment, the pair of transfer elements 180 simultaneously move in the same direction. For example, a first transfer element 180 a moves back from the position in FIG. 12 to an exit position for the vacuum chamber 130 where it will receive a platen 114 leaving the vacuum chamber 130, while a second transfer element 180 b moves a freshly loaded platen 114 from the loading station to an entry position for the vacuum chamber 130. The platens 114 may slide across and be guided by a track 182 that is positioned within the housing 112 at least along a portion of the path. FIG. 13 shows the first transfer element 180 a and the second transfer element 180 b engaged in this type of simultaneous movement.

While FIGS. 12-13 illustrate the machine 110 with an upper portion removed to view the working elements within the machine 110, FIG. 14 illustrates the machine 110 in cross-section as well so as to view the interaction of the platens 114 and the vacuum chamber 130. Specifically, the first platen 114 a is now located at the entry point for the vacuum chamber 130. The bottom structure 132 has been retracted from the top structure 134, as the second platen 114 b has now received the film through the vacuum-skin packaging process within the chamber 130.

As shown in FIG. 15, the first platen 114 a is moved through a pneumatically controlled arm (not shown) from the first transfer element 180 a into the vacuum chamber 130. When doing so, the second platen 114 b is urged towards the first transfer element 180 a where it will reside for the next movement along the path. The platens 114 also may be removed from the vacuum chamber 130 by use of an additional pneumatically controlled arm. As shown in FIG. 16, the bottom structure 132 is moved upwardly into sealing engagement with the top structure 134 while the first platen 114 a is located therein. The processes described above in FIGS. 1-11 for placing the heated film over the first platen 114 a may now occur.

In FIG. 17, the transfer elements 180 have moved back towards their original position. In doing so, the first transfer element 180 a has moved the second platen 114 b through a cutting station 190 where the film is cut around each of the trays 116. Grooves and slots may be present in the platen 114 b to facilitate cutting in multiple directions (e.g., perpendicular directions). The cutting station 190 preferably includes a first set of rotary knives 195 that cut the film in a first direction as they leave the vacuum chamber 130, and a second set of rotary knives 198 that cut the film in a second direction as the platen 114 b advances toward the unloading position. As show, each set of knives 195, 198 includes three rotary knives to cut around the periphery of the four trays 116 within from the platen 114. Cutting may also be done manually. When the second platen 114 b reaches the unloading position along the continuous path as shown in FIG. 18, each of the trays 116 is now free to be removed from the platen 114 b.

As shown in FIG. 19, the second platen 114 b has had four packaged trays 116 a-116 d removed (for example by manually pulling each of the four trays 116 a-116 d from the platen 114 b). A pneumatic arm then moves the second platen 114 b towards the third platen 114 c, which causes the third platen 114 c to be urged into the loading station. At this point the third platen 114 c receives a plurality of trays 116 with product 118. As such, a full cycle is complete (relative to FIG. 12) in that one platen 114 c is filled with trays 116 and product at the loading station, one platen 114 a is still located in the vacuum chamber 130 where it is undergoing the vacuum skin packaging process, and one platen 114 b is now located adjacent to the loading station.

One of the benefits of the present invention is that the machines 10, 110 can receive different platens that are configured to receive different styles and shapes of trays. Accordingly, the first platen may have two large trays with a first type of product, but a second platen processed immediately thereafter may have eight small trays with different types of products. As long as the platen has exterior dimensions to be automatically transferred along the generally horizontal linear path of the machine 10 or the continuous cyclical path of the machine 110, its interior structures that hold the platens may be different. Furthermore, the present invention contemplates that the machine 10 and the machine 110 may utilize the same style platen, such that the platen design itself is modular in an array of different vacuum skin packaging machines.

FIGS. 20A, 20B, and 20C illustrate another exemplary platen 214 in more detail. The platen 214 is similar to the platens 14 and 114 in the previous embodiments. The platen 214 has four individual regions for receiving trays 216, but other platens 214 for receiving different types, sizes, or numbers of trays can be used within the machines. The platen 214 includes grooves 220 along the regions of the platen 214 adjacent to each of the trays 216. Each of the grooves 220 is for receiving the cutting mechanism (e.g., a rotary knife, straight knife, or razor) after the film has been attached over the trays 216. The cutting mechanism is inserted into the grooves 220 for cutting the film.

Preferably, the platen 214 is made from a metal, preferably aluminum, and each of the grooves 220 is fitted with an insert 225. The insert 225 is preferably a polymeric material, such as nylon. When the insert 225 is a polymeric material (preferably nylon), the film that is being heated in the vacuum chamber is held nicely against the insert during the cutting process. The insert 225 also serves the function of receiving the cutting mechanism and yielding to the cutting mechanism such that the sharp edges associated with the cutting mechanism is less prone to becoming dull during repetitive use. Moreover, if the inserts 225 become worn or contaminated after repetitive use, they can easily be replaced in the grooves 220 of the platen 214. Furthermore, the use of the metal (such as aluminum) for the platen 214 is beneficial in that it does not warp under the stresses and heat encountered throughout the packaging process described above. However, it should be noted that the present invention contemplates that the platen 214 can be made of other materials, such as rigid plastics, that are encounter less warp produced by heat and stress.

The platen 214 may have adjustable walls that are movable by screw mechanisms to accommodate various sizes and/or shapes of the trays. Alternatively, the internal structure of the platen 214 that defines the tray-receiving regions is removable and/or replaceable with other various shaped internal structures to accommodate various sizes and/or shapes of the trays.

Each of these embodiments and obvious variations thereof is contemplated as falling within the spirit and scope of the claimed invention, which is set forth in the following claims. Moreover, the present concepts expressly include any and all combinations and subcombinations of the preceding elements and aspects. 

What is claimed is:
 1. A method for providing a vacuum-skin packaging for products on trays using a vacuum chamber defined by a top structure and a bottom structure, comprising: while the bottom structure is retracted away from the top structure, automatically moving a platen along a path that extends into the vacuum chamber, the platen holding one or more of the trays; positioning a film over the platen; after the platen is positioned within the vacuum chamber, moving the bottom structure upwardly against the top structure so as to form a seal between the top structure and the bottom structure; creating a vacuum within the vacuum chamber, the film dividing the vacuum chamber into an upper volume and a lower volume; heating the film; venting the upper volume above the platen to force the heated film onto the platen and the one or more trays; retracting the bottom structure from the top structure of the vacuum chamber; and after the retracting, automatically moving the platen along the path out of the vacuum chamber.
 2. The method of claim 1, wherein the automatic moving of the platen along the path into or out of the vacuum chamber is in response to activating at least one of a power-driven roller or a power-driven slide element.
 3. The method of claim 1, wherein the automatic moving of the platen along the path out of the vacuum chamber is in response to a second platen engaging the platen as the second platen enters the vacuum chamber.
 4. The method of claim 1, wherein the heating the film occurs by use of a heating plate located within the upper structure adjacent to the film.
 5. The method of claim 1, wherein the positioning the film occurs though an automated film-feeding mechanism that pulls the film from a web into the vacuum chamber in a direction that is generally parallel to the path of the platen.
 6. The method of claim 1, wherein the platen holds a plurality of the trays, and the method further includes cutting the film in multiple directions with a plurality of knives to create individual packaged trays that can be independently removed from the platen.
 7. The method of claim 1, wherein the platen is held within the vacuum chamber via a stationary platform located within the bottom structure, the stationary platform being supported by at least one elongated support member, the bottom structure includes at least one opening for receiving the at least one elongated support member.
 8. The method of claim 7, wherein the at least one elongated support member includes an internal air conduit that is used to for creating the vacuum within the low volume.
 9. The method of claim 1, further including, after the trays have been removed from the platen after exiting the vacuum chamber, transferring the platen along a path that returns the platen to an entry point where non-filmed trays can be loaded on the platen and the platen can re-enter vacuum chamber.
 10. The method of claim 1, further including venting the lower volume after the venting of the upper volume.
 11. A vacuum-skin packaging machine for sealing film onto a tray containing a product, comprising: a vacuum system including a vacuum pump, piping, and valves; a top structure and a bottom structure defining a chamber, the chamber being in communication with the vacuum pump via the piping; an actuating mechanism to transition the top structure and the bottom structure between (i) an opened state whereby the top structure and the bottom structure are separated and (ii) a closed state whereby the top structure and the bottom structure are sealed together; and a first platen-movement mechanism to automatically move a platen from an in-feed position to within the chamber while the top structure and bottom structure are in the opened state, the platen holding the tray; and a heating plate to heat the film while the top structure and bottom structure are in the closed position, the heated film being forced against the platen and the tray in response to one or more of the valves venting a region of the chamber adjacent to the heated film.
 12. The vacuum-skin packaging machine of claim 11, further including a second platen-moving mechanism to automatically move the platen from the chamber after receiving the heated film.
 13. The vacuum-skin packaging machine of claim 11, further including an automatic film-feeding mechanism to move the film into the chamber when the top structure and the bottom structure are in the opened state.
 14. The vacuum-skin packaging machine of claim 13, further including an automatic film-cutting mechanism outside the chamber to cut the film after the top structure and the bottom structure are in the closed state.
 15. The vacuum-skin packaging machine of claim 11, further including a cutting station along the path outside the chamber, the cutting station automatically cutting the film that is attached to the trays on the platen in multiple directions with a plurality of knives.
 16. The vacuum-skin packaging machine of claim 11, further including platen-support structures to define a continuous platen-movement path on which the platens move from a loading station where trays are loaded on the platen, then to the chamber where the film is sealed against the trays, then to a removal station where the filmed trays are removed from the platens, and then back to the loading station.
 17. The vacuum-skin packaging machine of claim 16, further including platen-moving mechanisms that automatically move the platens around the continuous platen-movement path.
 18. A vacuum-skin packaging machine for sealing film onto a tray containing a product, comprising: a vacuum system including a vacuum pump, piping, and valves; a top structure and a bottom structure defining a chamber, the top structure and the bottom structure being transitionable between (i) an opened position whereby the top structure and the bottom structure are separated and platens can enter and exit the chamber and (ii) a closed position whereby the top structure and the bottom structure are sealed together to create a vacuum chamber in which heat is applied to the film to attach the film to the trays on the platens; and a continuous platen-movement path on which the platens move from a loading station where trays are loaded on the platen, into the vacuum chamber where the film is sealed against the trays, to a removal station where the filmed trays are removed from the platens, and back to the loading station.
 19. The vacuum-skin packaging machine of claim 18, wherein the continuous platen-movement path further includes one or more cutting station located after the vacuum chamber and before the removal station, the cutting station automatically cutting the film in multiple directions with a plurality of knives.
 20. The vacuum-skin packaging machine of claim 18, further including a vacuum system including a vacuum pump, a first set of piping, and a second set of piping, the first set of piping being in communication with an upper volume located above the film within the vacuum chamber, the second set of piping being in communication with a lower volume located below the film within the vacuum chamber 